1. Field of the Invention
This invention relates to a fiber optical measuring device for measuring physical quantities, such as temperature and pressure, comprising a transducer comprising a sensor material, an electronic unit, and light-conducting fiber means connecting the transducer to the electronic unit.
The expression "light" which is used in this specification should be taken to include electromagnetic radiation within the UV range, the visible range, and the IR range.
2. Description of the Prior Art
It is previously known from U.S. patent application Ser. No. 194,397, filed in the names of Olov Engstrom and Christer Ovren on Oct. 16th, 1980 now U.S. Pat. No. 4,376,890 and assigned with the present application to a common assignee, to provide a fiber-optic temperature-measuring apparatus in which a temperature is measured by illuminating a temperature-dependent photo-luminescent semiconductor material via one or more light-conducting fibers, sensing the absorption or luminescence of the illuminated semiconductor material via one or more light-conducting fibers, and utilizing the measured absorption and luminescence values to obtain a measure of the temperature of the semiconductor material. However, a disadvantage with this known apparatus is that it is very sensitive to variations in fiber damping and drift of light sources and detectors and therefore it is necessary to provide a spectral analysis of the light from the semiconductor material.
The present invention aims to provide a solution to the above-mentioned problems and other problems associated therewith. The problems are eliminated by measuring the dynamics of the absorption or luminescence processes instead of measuring the absolute values of the absorption or the luminescence.